This invention relates to the structure of a magnetoresistive element (which will be abbreviated hereinafter as an MR element), and more particularly to a structure which ensures uniform flow of current through a shunt biased MR element comprising a magnetoresistive film (which will be abbreviated hereinafter as an MR film) and a conductor film making electrical contact with the MR film.
A magnetic head employing an MR film (which head will be abbreviated hereinafter as an MR head) is now being widely used. In the case of such an MR head, it is necessary to externally apply a predetermined magnetic field in order to improve the sensitivity and linearity of the MR film. This magnetic field is called a bias magnetic field, and various methods including (1) a method of disposing a permanent magnet in the neighborhood of the MR film, (2) a method of disposing a conductor film in contact with the MR film, and (3) a method of disposing a soft magnetic film in the neighborhood of the MR film, have been proposed hitherto. Especially, the method described in (2) is called a shunt biasing method, and such a shunt biasing method is disclosed in, for example, U.S. Pat. No. 3,967,368. This U.S. patent shows an arrangement as shown in FIG. 1. Referring to FIG. 1, both a sensor part 10 exhibiting a magnetoresistive effect in response to an externally applied magnetic field and leads 20 and 25 supplying a predetermined current to the sensor part 10 to produce a bias magnetic field and deriving a change in the resistance of the sensor part 10 as a voltage change are made of an MR film and a conductor film. However, in the structure of the shunt biased MR element shown in FIG. 1, no consideration was given to the widths W and W' of the leads 20 and 25 at the surface of the shunt biased MR element remote from the surface 15 facing a recording medium. Further, the relation between the sensor part 10 and the leads 20, 25 was not also considered. As a result, a uniform current did not always flow through the sensor part 10, and the desired bias magnetic field could not be applied to the MR film.